1. Field of the Invention
The invention relates to an image forming apparatus for detecting an abnormality of a sheet processing apparatus.
2. Description of the Related Art
Hitherto, an image forming system in which a plurality of post-processing apparatuses are connected to an image forming apparatus in tandem and predetermined post-processes are executed has been known. In such an image forming system, in order to avoid such a situation that the whole system cannot be used if an error occurred in one post-processing apparatus, a selecting portion to select use/non-use of the post-processing apparatus is provided. The non-use of the error-occurred post-processing apparatus is clearly selected in the selecting portion, thereby making control so that a part of the whole system can be used without disabling the whole system to be used (Japanese Patent Application Laid-open No. H09-301618.
However, the above conventional image forming system has the following problems. After the error occurred, by disconnecting the error-occurred apparatus from the image forming system, it is possible to avoid such a situation that the whole system cannot be used. However, when the error has occurred, since the whole image forming system is temporarily halted, for example, even in the case where an inputted job is not concerned with the error-occurred apparatus, such a job cannot be continued.
If an abnormality is detected in communication with a sheet processing apparatus for a period of time during which a power source of the image forming system is actually turned off after the operation to turn off the power source was executed, there is a case where in spite of the fact that a flow for turning off the power source has been predetermined, an error process is executed and an operability deteriorates.